1. Field of the Invention
The present invention relates to an optical disc apparatus for recording and/or reproducing data on an optical disc such as a CD (compact disc) or a DVD (digital versatile disc).
2. Description of the Related Art
In the optical disc apparatus, data are reproduced from the optical disc such as the CD or DVD, and the data are recorded on recordable optical disc such as a CD-R, CD-RW, DVD-R, DVD-RW, or the like by an optical head called “optical pickup”. Data recording tracks are formed concentrically or spirally on such the optical disc. The optical pickup is constituted for emitting light beams such as laser beams by a laser diode, for focusing the light beams on the data recording face of the optical disc through an objective lens, for receiving a reflected light reflected from a data recording face of the optical disc and converting variation of intensity of the reflected light to electric signals by a photo-sensor and for outputting the electric signals. The optical pickup is moved in a radial direction of the optical disc.
For reproducing the data from the optical disc or for recording the data on the optical disc, the optical pickup is moved in the radial direction of the optical disc for facing a data recording track on which the data are recorded or to be recorded. The laser diode of the optical pickup emits a light beam and the light beam is focused on the data recording track by the objective lens, while the optical disc is rotated.
For reproducing the data from the optical disc, the objective lens of the optical pickup is moved in a direction perpendicular to the data recording face of the optical disc in a manner so that the concentration point of the focused light beam is just placed on the data recording face of the optical disc. Subsequently, the objective lens of the optical pickup is moved in the radial direction of the optical disc in a manner so that the concentration point of the focused light beam is just placed on the data recording track on the optical disc, while the concentration point of the focused light beam is placed on the data recording face of the optical disc.
Such the focusing and tracking operations of the optical pickup are controlled corresponding to the electric signals outputted from the photo-sensor of the optical pickup. Pits formed on the data recording tracks on the optical disc are sensed from the electric signals outputted from the photo-sensor of the optical pickup, while the light beam is focused and tracked on the data recording track on the optical disc. Thus, the data are read out from the optical disc and will be reproduced.
For recording the data on the optical disc, pits corresponding to the data to be recorded are formed on the data recording tracks by concentrating the light beams pulsatively on the data recording track on the optical disc by the laser diode of the optical pickup.
When the optical disc is read-only use on which data of sounds or video images are recorded, information data for showing the contents or operation program are recorded in the innermost data recording area on the data recording face of the optical disc. When the optical disc is recordable by a user, the information data are sequentially recorded on the data recording tracks in the innermost data recording area from the inside.
When an optical disc is loaded on the optical disc apparatus, the optical disc apparatus executes an initial reading operation for reading out the information data from the innermost data recording area. Subsequently, the optical disc apparatus judges the kinds of the optical disc and the contents of the information data and controls the recording or reproducing operation corresponding to the information data read out from the optical disc in the initial reading operation. In such the initial reading operation, the optical pickup is placed at an initial reading position a little outside from the innermost edge of the data recording area on the optical disc, at the start. The light beam emitted from the laser diode of the optical pickup is focused on a position on the data recording area facing the initial reading position of the optical pickup.
In a conventional optical disc apparatus, which is, for example, shown in publication gazette of Japanese patent application 11-53836, it is judged whether user data are recorded in a data recording area or not when other data are recorded in a data recording area on an optical disc or reproduced from the data recording area on an optical disc so as not to break the user data recorded on the optical disc.
When a recordable optical disc, on which the information data are recorded a little, is loaded on the conventional optical disc apparatus, the initial reading position of the optical pickup is sometimes placed outside from the data recording tracks on which the information data are recorded. In such the case, no pit is formed on the position or track on which the light beam is focused, so that it is impossible to track the light beam on the data recording track. Thus, the information data cannot be read out from the optical disc due to missing the focusing of the light beam. When the focusing of the light beam is missed, the initial reading operation will be retried in several times. The information data recorded in the innermost data recording area, however, cannot be read out by retrying the initial reading operation in many cases. Even when the information data can be read out by retrying the initial reading operation, it wastes a lot of time.